package Easy.Tree;

/**
 * @author: white-zhou
 * @date: 2024-09-19 17:31
 **/
public class MergeTrees {
    public static class TreeNode {
        int val;
        TreeNode left;
        TreeNode right;
        TreeNode() {}
        TreeNode(int val) { this.val = val; }
        TreeNode(int val, TreeNode left, TreeNode right) {
            this.val = val;
            this.left = left;
            this.right = right;
        }
    }

    public TreeNode mergeTrees(TreeNode root1, TreeNode root2) {
        // 递归
        if (root1 == null) {
            return root2;
        }
        if (root2 == null) {
            return root1;
        }
        // 合并根节点
        root1.val += root2.val;
        // 递归合并左右子树
        root1.left = mergeTrees(root1.left, root2.left);
        root1.right = mergeTrees(root1.right, root2.right);
        // 返回合并后的树
        return root1;
    }
}
